Reduction of antibiotic resistance genes (ARGs) in swine manure-fertilized soil via fermentation broth from fruit and vegetable waste

Abstract

The issue of growing increase of antibiotic resistance genes (ARGs) in manure-fertilized soil needs urgently addressing. In this study, fermentation broth from fruit and vegetable waste was prepared to reduce ARG abundance in swine manure-fertilized soils. With a six-month field experiment, we found that swine manure-fertilized soil had significantly higher ARG abundance than soil applied with chemical fertilizer. As expected, the homemade fermentation broth significantly reduced ARG abundance in swine manure-fertilized soil, possibly through the decrease of abundance of Actinomyces, in which there was a 48.0%, 51.9%, and 66.7% decrease in the abundance of Nocardioides, Streptomyces, and Nonomuraea, respectively. With the bacteriostatic experiment, we observed that fermentation broth (5 mL/L) significantly inhibited the growth and metabolism in Actinomycetes spp. and Nocardioides sp., in terms of ATPase and PDH activity. These findings confirmed that the inhibition of Actinobacteria, some of the most dominant ARG hosts, was one of the main mechanisms responsible for the decrease in ARG abundance in fermentation broth-treated soil. This study provides field-scale evidence of a feasible strategy for controlling farmland ARG pollution, which is of utmost importance for soil health in the context of sustainable agriculture.

Keywords: Actinobacteria; Bacterial community; Farmland soil; Host strains; MGEs.